Synergistic Chemoimmunotherapy of Epithelial Ovarian Cancer Using ErbB-Retargeted T Cells Combined with Carboplatin

Enhancing cellular immunotherapies in cancer by engineering selective therapeutic resistance

Adoptive cell therapies engineered to express chimeric antigen receptors (CARs) or transgenic T cell receptors (TCRs) to recognize and eliminate cancer cells have emerged as a promising approach for achieving long-term remissions in patients with cancer. To be effective, the engineered cells must persist at therapeutically relevant levels while avoiding off-tumour toxicities, which has been challenging to realize outside of B cell and plasma cell malignancies. This Review discusses concepts to enhance the efficacy, safety and accessibility of cellular immunotherapies by endowing cells with selective resistance to small-molecule drugs or antibody-based therapies to facilitate combination therapies with substances that would otherwise interfere with the functionality of the effector cells. We further explore the utility of engineering healthy haematopoietic stem cells to confer resistance to antigen-directed immunotherapies and small-molecule targeted therapies to expand the therapeutic index of said targeted anticancer agents as well as to facilitate in vivo selection of gene-edited haematopoietic stem cells for non-malignant applications. Lastly, we discuss approaches to evade immune rejection, which may be required in the setting of allogeneic cell therapies. Increasing confidence in the tools and outcomes of genetically modified cell therapy now paves the way for rational combinations that will open new therapeutic horizons.

Recent advances in CAR T-cell engineering using synthetic biology: Paving the way for next-generation cancer treatment

This book chapter highlights a comprehensive exploration of the transformative innovations in the field of cancer immunotherapy. CAR (Chimeric Antigen Receptor) T-cell therapy represents a groundbreaking approach to treat cancer by reprogramming a patient immune cells to recognize and destroy cancer cells. This chapter underscores the critical role of synthetic biology in enhancing the safety and effectiveness of CAR T-cell therapies. It begins by emphasizing the growing importance of personalized medicine in cancer treatment, emphasizing the shift from one-size-fits-all approaches to patient-specific solutions. Synthetic biology, a multidisciplinary field, has been instrumental in customizing CAR T-cell therapies, allowing for fine-tuned precision and minimizing unwanted side effects. The chapter highlights recent advances in gene editing, synthetic gene circuits, and molecular engineering, showcasing how these technologies are optimizing CAR T-cell function. In summary, this book chapter sheds light on the remarkable progress made in the development of CAR T-cell therapies using synthetic biology, providing hope for cancer patients and hinting at a future where highly personalized and effective cancer treatments are the norm.

Evolving CAR-T-Cell Therapy for Cancer Treatment: From Scientific Discovery to Cures

In recent years, chimeric antigen receptor (CAR)-T-cell therapy has emerged as the most promising immunotherapy for cancer that typically uses patients' T cells and genetically engineered them to target cancer cells. Although recent improvements in CAR-T-cell therapy have shown remarkable success for treating hematological malignancies, the heterogeneity in tumor antigens and the immunosuppressive nature of the tumor microenvironment (TME) limits its efficacy in solid tumors. Despite the enormous efforts that have been made to make CAR-T-cell therapy more effective and have minimal side effects for treating hematological malignancies, more research needs to be conducted regarding its use in the clinic for treating various other types of cancer. The main concern for CAR-T-cell therapy is severe toxicities due to the cytokine release syndrome, whereas the other challenges are associated with complexity and immune-suppressing TME, tumor antigen heterogeneity, the difficulty of cell trafficking, CAR-T-cell exhaustion, and reduced cytotoxicity in the tumor site. This review discussed the latest discoveries in CAR-T-cell therapy strategies and combination therapies, as well as their effectiveness in different cancers. It also encompasses ongoing clinical trials; current challenges regarding the therapeutic use of CAR-T-cell therapy, especially for solid tumors; and evolving treatment strategies to improve the therapeutic application of CAR-T-cell therapy.

Effect of neoadjuvant chemotherapy on the immune microenvironment of gynaecological tumours

Purpose: To assess the impact of neoadjuvant chemotherapy (NACT) on the tumor immune microenvironment (TIME) in gynaecological tumors, with a focus on understanding the potential for enhanced combination therapies.Methods: We systematically queried the PubMed, Embase, and Cochrane databases, encompassing reviews, clinical trials, and case studies, to undertake a thorough analysis of the impact of NACT on the TIME of gynaecological tumors.Results: NACT induces diverse immune microenvironment changes in gynaecological tumors. In cervical cancer, NACT boosts immune-promoting cells, enhancing tumor clearance. Ovarian cancer studies yield variable outcomes, influenced by patient-specific factors and treatment regimens. Limited research exists on NACT's impact on endometrial cancer's immune microenvironment, warranting further exploration. In summary, NACT-induced immune microenvironment changes display variability. Clinical trials highlight personalized immunotherapy's positive impact on gynaecological tumor prognosis, suggesting potential avenues for future cancer treatments. However, rigorous investigation is needed to determine the exact efficacy and safety of combining NACT with immunotherapy.Conclusion: This review provides a solid foundation for the development of late-stage immunotherapy and highlights the importance of therapeutic strategies targeting immune cells in TIME in anti-tumor therapy.

Intratumoral pan-ErbB targeted CAR-T for head and neck squamous cell carcinoma: interim analysis of the T4 immunotherapy study

BACKGROUND

Locally advanced/recurrent head and neck squamous cell carcinoma (HNSCC) is associated with significant morbidity and mortality. To target upregulated ErbB dimer expression in this cancer, we developed an autologous CD28-based chimeric antigen receptor T-cell (CAR-T) approach named T4 immunotherapy. Patient-derived T-cells are engineered by retroviral transduction to coexpress a panErbB-specific CAR called T1E28ζ and an IL-4-responsive chimeric cytokine receptor, 4αβ, which allows IL-4-mediated enrichment of transduced cells during manufacture. These cells elicit preclinical antitumor activity against HNSCC and other carcinomas. In this trial, we used intratumoral delivery to mitigate significant clinical risk of on-target off-tumor toxicity owing to low-level ErbB expression in healthy tissues.

METHODS

We undertook a phase 1 dose-escalation 3+3 trial of intratumoral T4 immunotherapy in HNSCC (NCT01818323). CAR T-cell batches were manufactured from 40 to 130 mL of whole blood using a 2-week semiclosed process. A single CAR T-cell treatment, formulated as a fresh product in 1-4 mL of medium, was injected into one or more target lesions. Dose of CAR T-cells was escalated in 5 cohorts from 1×107-1×109 T4+ T-cells, administered without prior lymphodepletion.

RESULTS

Despite baseline lymphopenia in most enrolled subjects, the target cell dose was successfully manufactured in all cases, yielding up to 7.5 billion T-cells (67.5±11.8% transduced), without any batch failures. Treatment-related adverse events were all grade 2 or less, with no dose-limiting toxicities (Common Terminology Criteria for Adverse Events V.4.0). Frequent treatment-related adverse events were tumor swelling, pain, pyrexias, chills, and fatigue. There was no evidence of leakage of T4+ T-cells into the circulation following intratumoral delivery, and injection of radiolabeled cells demonstrated intratumoral persistence. Despite rapid progression at trial entry, stabilization of disease (Response Evaluation Criteria in Solid Tumors V.1.1) was observed in 9 of 15 subjects (60%) at 6 weeks post-CAR T-cell administration. Subsequent treatment with pembrolizumab and T-VEC oncolytic virus achieved a rapid complete clinical response in one subject, which was durable for over 3 years. Median overall survival was greater than for historical controls. Disease stabilization was associated with the administration of an immunophenotypically fitter, less exhausted, T4 CAR T-cell product.

CONCLUSIONS

These data demonstrate the safe intratumoral administration of T4 immunotherapy in advanced HNSCC.

CAR-T Cells in the Treatment of Ovarian Cancer: A Promising Cell Therapy

Ovarian cancer (OC) is among the most common gynecologic malignancies with a poor prognosis and a high mortality rate. Most patients are diagnosed at an advanced stage (stage III or IV), with 5-year survival rates ranging from 25% to 47% worldwide. Surgical resection and first-line chemotherapy are the main treatment modalities for OC. However, patients usually relapse within a few years of initial treatment due to resistance to chemotherapy. Cell-based therapies, particularly adoptive T-cell therapy and chimeric antigen receptor T (CAR-T) cell therapy, represent an alternative immunotherapy approach with great potential for hematologic malignancies. However, the use of CAR-T-cell therapy for the treatment of OC is still associated with several difficulties. In this review, we comprehensively discuss recent innovations in CAR-T-cell engineering to improve clinical efficacy, as well as strategies to overcome the limitations of CAR-T-cell therapy in OC.

CAR-cell therapy in the era of solid tumor treatment: current challenges and emerging therapeutic advances

In the last decade, Chimeric Antigen Receptor (CAR)-T cell therapy has emerged as a promising immunotherapeutic approach to fight cancers. This approach consists of genetically engineered immune cells expressing a surface receptor, called CAR, that specifically targets antigens expressed on the surface of tumor cells. In hematological malignancies like leukemias, myeloma, and non-Hodgkin B-cell lymphomas, adoptive CAR-T cell therapy has shown efficacy in treating chemotherapy refractory patients. However, the value of this therapy remains inconclusive in the context of solid tumors and is restrained by several obstacles including limited tumor trafficking and infiltration, the presence of an immunosuppressive tumor microenvironment, as well as adverse events associated with such therapy. Recently, CAR-Natural Killer (CAR-NK) and CAR-macrophages (CAR-M) were introduced as a complement/alternative to CAR-T cell therapy for solid tumors. CAR-NK cells could be a favorable substitute for CAR-T cells since they do not require HLA compatibility and have limited toxicity. Additionally, CAR-NK cells might be generated in large scale from several sources which would suggest them as promising off-the-shelf product. CAR-M immunotherapy with its capabilities of phagocytosis, tumor-antigen presentation, and broad tumor infiltration, is currently being investigated. Here, we discuss the emerging role of CAR-T, CAR-NK, and CAR-M cells in solid tumors. We also highlight the advantages and drawbacks of CAR-NK and CAR-M cells compared to CAR-T cells. Finally, we suggest prospective solutions such as potential combination therapies to enhance the efficacy of CAR-cells immunotherapy.

Towards Novel Gene and Cell Therapy Approaches for Cervical Cancer

Cervical cancer is one of the most common malignancies in women, and the majority of cases are caused by infection with high-risk human papilloma virus (HPV) subtypes. Despite effective preventative measures, such as vaccinations against HPV, over 300,000 women die world-wide from cervical cancer each year. Once cervical cancer is diagnosed, treatment may consist of radial hysterectomy, or chemotherapy and radiotherapy, or a combination of therapies dependent upon the disease stage. Unfortunately, overall prognosis for patients with metastatic or recurrent disease remains poor. In these cases, immunotherapies may be useful based on promising preclinical work, some of which has been successfully translated to the clinic. For example, approaches using monoclonal antibodies directed against surface proteins important for control of immune checkpoints (i.e., immune checkpoint inhibitors) were shown to improve outcome in many cancer settings, including cervical cancer. Additionally, initial clinical studies showed that application of cytotoxic immune cells modified to express chimeric antigen receptors (CAR) or T cell receptors (TCR) for better recognition and elimination of tumor cells may be useful to control cervical cancer. This review explores these important topics, including strengths and limitations of standard and developing approaches, and how some novel treatment strategies may be optimally used to offer the best possible treatment for cervical cancer patients.

CAR-T cell combination therapy: the next revolution in cancer treatment

In recent decades, the advent of immune-based therapies, most notably Chimeric antigen receptor (CAR)-T cell therapy has revolutionized cancer treatment. The promising results of numerous studies indicate that CAR-T cell therapy has had a remarkable ability and successful performance in treating blood cancers. However, the heterogeneity and immunosuppressive tumor microenvironment (TME) of solid tumors have challenged the effectiveness of these anti-tumor fighters by creating various barriers. Despite the promising results of this therapeutic approach, including tumor degradation and patient improvement, there are some concerns about the efficacy and safety of the widespread use of this treatment in the clinic. Complex and suppressing tumor microenvironment, tumor antigen heterogeneity, the difficulty of cell trafficking, CAR-T cell exhaustion, and reduced cytotoxicity in the tumor site limit the applicability of CAR-T cell therapy and highlights the requiring to improve the performance of this treatment. With this in mind, in the last decade, many efforts have been made to use other treatments for cancer in combination with tuberculosis to increase the effectiveness of CAR-T cell therapy, especially in solid tumors. The combination therapy results have promising consequences for tumor regression and better cancer control compared to single therapies. Therefore, this study aimed to comprehensively discuss different cancer treatment methods in combination with CAR-T cell therapy and their therapeutic outcomes, which can be a helpful perspective for improving cancer treatment in the near future.

Ligand-based CAR-T cell: Different strategies to drive T cells in future new treatments

Chimeric antigen receptor (CAR)-based therapies are presented as innovative treatments for multiple malignancies. Despite their clinical success, there is scientific evidence of the limitations of these therapies mainly due to immunogenicity issues, toxicities associated with the infusion of the product, and relapses of the tumor. As a result, novel approaches are appearing aiming to solve and/or mitigate the harmful effects of CAR-T therapies. These include strategies based on the use of ligands as binding moieties or ligand-based CAR-T cells. Several proposals are currently under development, with some undergoing clinical trials to assess their potential benefits. In addition to these, therapies such as chimeric autoantibody receptor (CAAR), B-cell receptor antigen for reverse targeting (BAR), and even chimeric human leukocyte antigen (HLA) antibody receptor (CHAR) have emerged, benefiting from the advantages of antigenic ligands as antibody-binding motifs. This review focuses on the potential role that ligands can play in current and future antitumor treatments and in other types of diseases, such as autoimmune diseases or problems associated with transplantation.

Update for Advance CAR-T Therapy in Solid Tumors, Clinical Application in Peritoneal Carcinomatosis From Colorectal Cancer and Future Prospects

Latest advances in the field of cancer immunotherapy have developed the (Chimeric Antigen Receptor) CAR-T cell therapy. This therapy was first used in hematological malignancies which obtained promising results; therefore, the use of CAR-T cells has become a popular approach for treating non-solid tumors. CAR-T cells consist of T-lymphocytes that are engineered to express an artificial receptor against any surface antigen of our choice giving us the capacity of offering precise and personalized treatment. This leaded to the development of CAR-T cells for treating solid tumors with the hope of obtaining the same result; however, their use in solid tumor and their efficacy have not achieved the expected results. The reason of these results is because solid tumors have some peculiarities that are not present in hematological malignancies. In this review we explain how CAR-T cells are made, their mechanism of action, adverse effect and how solid tumors can evade their action, and also we summarize their use in colorectal cancer and peritoneal carcinomatosis.

The antigen-binding moiety in the driver's seat of CARs

Immuno-oncology has been at the forefront of cancer treatment in recent decades. In particular immune checkpoint and chimeric antigen receptor (CAR)-T cell therapy have achieved spectacular results. Over the years, CAR-T cell development has followed a steady evolutionary path, focusing on increasing T cell potency and sustainability, which has given rise to different CAR generations. However, there was less focus on the mode of interaction between the CAR-T cell and the cancer cell; more specifically on the targeting moiety used in the CAR and its specific properties. Recently, the importance of optimizing this domain has been recognized and the possibilities have been exploited. Over the last 10 years-in addition to the classical scFv-based CARs-single domain CARs, natural receptor-ligand CARs, universal CARs and CARs targeting more than one antigen have emerged. In addition, the specific parameters of the targeting domain and their influence on T cell activation are being examined. In this review, we concisely present the history of CAR-T cell therapy, and then expand on various developments in the CAR ectodomain. We discuss different formats, each with their own advantages and disadvantages, as well as the developments in affinity tuning, avidity effects, epitope location, and influence of the extracellular spacer.

Advances in CAR design

Chimeric antigen receptor (CAR) T cells have revolutionized the management of B cell malignancies. These synthetic molecules are composed of peptide fragments from several distinct immune cell proteins and link highly-specific antigen recognition with potent T cell activation. Despite impressive results in many, less than half of patients treated will achieve durable remission after CAR therapy. Recent studies have identified the central role that each structural component of the CAR molecule plays in regulating T cell function. Significant effort has been dedicated to exploring strategies to improve the design of CARs themselves or integrate their activity with other regulatory circuits to enable more precise function. In this review, we will summarize recent pre-clinical and clinical studies that have evaluated novel CAR design formats.

Strategic Combination Therapies for Ovarian Cancer

Ovarian cancer remains the leading cause of gynecologic cancer-related deaths among women worldwide. The dismal survival rate is partially due to recurrence after standardized debulking surgery and first-line chemotherapy. In recent years, targeted therapies, including antiangiogenic agents or poly (ADP-ribose) polymerase inhibitors, represent breakthroughs in the treatment of ovarian cancer. As more therapeutic agents become available supplemented by a deeper understanding of ovarian cancer biology, a range of combination treatment approaches are being actively investigated to further improve the clinical outcomes of the disease. These combinations, which involve DNA-damaging agents, targeted therapies of signaling pathways and immunotherapies, simultaneously target multiple cancer pathways or hallmarks to induce additive or synergistic antitumor activities. Here we review the preclinical data and ongoing clinical trials for developing effective combination therapies in treating ovarian cancer. These emerging therapeutic modalities may reshape the treatment landscape of the disease.

Development and Validation of a Good Manufacturing Process for IL-4-Driven Expansion of Chimeric Cytokine Receptor-Expressing CAR T-Cells

Adoptive cancer immunotherapy using chimeric antigen receptor (CAR) engineered T-cells holds great promise, although several obstacles hinder the efficient generation of cell products under good manufacturing practice (GMP). Patients are often immune compromised, rendering it challenging to produce sufficient numbers of gene-modified cells. Manufacturing protocols are labour intensive and frequently involve one or more open processing steps, leading to increased risk of contamination. We set out to develop a simplified process to generate autologous gamma retrovirus-transduced T-cells for clinical evaluation in patients with head and neck cancer. T-cells were engineered to co-express a panErbB-specific CAR (T1E28z) and a chimeric cytokine receptor (4αβ) that permits their selective expansion in response to interleukin (IL)-4. Using peripheral blood as starting material, sterile culture procedures were conducted in gas-permeable bags under static conditions. Pre-aliquoted medium and cytokines, bespoke connector devices and sterile welding/sealing were used to maximise the use of closed manufacturing steps. Reproducible IL-4-dependent expansion and enrichment of CAR-engineered T-cells under GMP was achieved, both from patients and healthy donors. We also describe the development and approach taken to validate a panel of monitoring and critical release assays, which provide objective data on cell product quality.

SJI 2020 special issue: A catalogue of Ovarian Cancer targets for CAR therapy

Ovarian Cancer (OC) is currently difficult to cure, mainly due to its late detection and the advanced state of the disease at the time of diagnosis. Therefore, conventional treatments such as debulking surgery and combination chemotherapy are rarely able to control progression of the tumour, and relapses are frequent. Alternative therapies are currently being evaluated, including immunotherapy and advanced T cell-based therapy. In the present review, we will focus on a description of those Chimeric Antigen Receptors (CARs) that have been validated in the laboratory or are being tested in the clinic. Numerous target antigens have been defined due to the identification of OC biomarkers, and many are being used as CAR targets. We provide an exhaustive list of these constructs and their current status. Despite being innovative and efficient, the OC-specific CARs face a barrier to their clinical efficacy: the tumour microenvironment (TME). Indeed, effector cells expressing CARs have been shown to be severely inhibited, rendering the CAR T cells useless once at the tumour site. Herein, we give a thorough description of the highly immunosuppressive OC TME and present recent studies and innovations that have enabled CAR T cells to counteract this negative environment and to destroy tumours.

RNA-electroporated T cells for cancer immunotherapy

Adoptive T cell therapy has proven effective against hematologic malignancies and demonstrated efficacy against a variety of solid tumors in preclinical studies and clinical trials. Nonetheless, antitumor responses against solid tumors remain modest, highlighting the need to enhance the effectiveness of this therapy. Genetic modification of T cells with RNA has been explored to enhance T-cell antigen specificity, effector function, and migration to tumor sites, thereby potentiating antitumor immunity. This review describes the rationale for RNA-electroporated T cell modifications and provides an overview of their applications in preclinical and clinical investigations for the treatment of hematologic malignancies and solid tumors.

Programming CAR T cells to enhance anti-tumor efficacy through remodeling of the immune system

Chimeric antigen receptor (CAR) T cells have been indicated effective in treating B cell acute lymphoblastic leukemia and non-Hodgkin lymphoma and have shown encouraging results in preclinical and clinical studies. However, CAR T cells have achieved minimal success against solid malignancies because of the additional obstacles of their insufficient migration into tumors and poor amplification and persistence, in addition to antigen-negative relapse and an immunosuppressive microenvironment. Various preclinical studies are exploring strategies to overcome the above challenges. Mobilization of endogenous immune cells is also necessary for CAR T cells to obtain their optimal therapeutic effect given the importance of the innate immune responses in the elimination of malignant tumors. In this review, we focus on the recent advances in the engineering of CAR T cell therapies to restore the immune response in solid malignancies, especially with CAR T cells acting as cellular carriers to deliver immunomodulators to tumors to mobilize the endogenous immune response. We also explored the sensitizing effects of conventional treatment approaches, such as chemotherapy and radiotherapy, on CAR T cell therapy. Finally, we discuss the combination of CAR T cells with biomaterials or oncolytic viruses to enhance the anti-tumor outcomes of CAR T cell therapies in solid tumors.

A brief review concerning Chimeric Antigen Receptors T cell therapy

The understanding concerning the function of immune system in cancer has achieved considerable advance with time passes by. Manipulating genetically engineered immune cells were investigated as a novel strategy for treating cancer. Chimeric antigen receptors (CARs) are recombinant protein molecules by merging the exquisite targeting the potent cytotoxicity of T cells and specificity of monoclonal antibodies and, which could trigger serial cascades of signal transduction and thereby activate T cells to directly destroy the tumor cells. Manufacturing CAR-modified T lymphocytes were successfully implemented in treating cancer derived from they could specifically retarget tumor-associated antigens, causing effective elimination of tumor cells, which spurred the optimization and development of new CAR-T cell technology. The advancement of synthetic biology methodologies of cell therapy in CAR-T would ultimately provide us with a much safer, reliable and efficient modality to against cancer. This review primarily described the emergence, development and application of cell therapy in CAR-T, then discuss the side effects and the potential factors of tumor reccurrence caused by CAR-T cell therapy, in addition to the corresponding countermeasure concerning complications.

CAR T cell therapy: newer approaches to counter resistance and cost

The genetically engineered Chimeric Antigen Receptor bearing T-cell (CAR T cell) therapy has been emerged as the new paradigm of cancer immunotherapy. However, recent studies have reported an increase in the number of relapsed haematological malignancies. This review provides newer insights into how the efficacy of CAR T cells might be increased by the application of new genome editing technologies, monitoring the complexity of tumor types and T cells sub-types. Next, tumor mutation burden along with tumormicroenvironment and epigenetic mechanisms of CAR T cell as well as tumor cell may play a vital role to tackle the cancer resistance mechanisms. These studies highlight the need to consider traditional cancer therapy in conjunction with CAR T cell therapy for relapsed or cases unresponsive to treatment. Of note, this therapy is highly expensive and requires multi-skill for successful implementation, which results in reduction of its accessibility/affordability to the patients. Here, we also propose a model for cost minimization of CAR T cell therapy by a collaboration of academia, hospitals and industry.

Chimeric antigen receptor T cells in solid tumors: a war against the tumor microenvironment

Chimeric antigen receptor (CAR) T cell is a novel approach, which utilizes anti-tumor immunity for cancer treatment. As compared to the traditional cell-mediated immunity, CAR-T possesses the improved specificity of tumor antigens and independent cytotoxicity from major histocompatibility complex molecules through a monoclonal antibody in addition to the T-cell receptor. CAR-T cell has proven its effectiveness, primarily in hematological malignancies, specifically where the CD 19 CAR-T cells were used to treat B-cell acute lymphoblastic leukemia and B-cell lymphomas. Nevertheless, there is little progress in the treatment of solid tumors despite the fact that many CAR agents have been created to target tumor antigens such as CEA, EGFR/EGFRvIII, GD2, HER2, MSLN, MUC1, and other antigens. The main obstruction against the progress of research in solid tumors is the tumor microenvironment, in which several elements, such as poor locating ability, immunosuppressive cells, cytokines, chemokines, immunosuppressive checkpoints, inhibitory metabolic factors, tumor antigen loss, and antigen heterogeneity, could affect the potency of CAR-T cells. To overcome these hurdles, researchers have reconstructed the CAR-T cells in various ways. The purpose of this review is to summarize the current research in this field, analyze the mechanisms of the major barriers mentioned above, outline the main solutions, and discuss the outlook of this novel immunotherapeutic modality.

Genetic Modification Strategies to Enhance CAR T Cell Persistence for Patients With Solid Tumors

Immunotherapy with chimeric antigen receptor (CAR) T cells offers a promising method to improve cure rates and decrease morbidities for patients with cancer. In this regard, CD19-specific CAR T cell therapies have achieved dramatic objective responses for a high percent of patients with CD19-positive leukemia or lymphoma. Most patients with solid tumors however, have experienced transient or no benefit from CAR T cell therapies. Novel strategies are therefore needed to improve CAR T cell function for patients with solid tumors. One obstacle for the field is limited CAR T cell persistence after infusion into patients. In this review we highlight genetic engineering strategies to improve CAR T cell persistence for enhancing antitumor activity for patients with solid tumors.

Chemotherapy-induced apoptosis, autophagy and cell cycle arrest are key drivers of synergy in chemo-immunotherapy of epithelial ovarian cancer

Epithelial ovarian cancer (EOC) is the most lethal of all gynecological malignancies in the UK. Recent evidence has shown that there is potential for immunotherapies to be successful in treating this cancer. We have previously shown the effective application of combinations of traditional chemotherapy and CAR (chimeric antigen receptor) T cell immunotherapy in in vitro and in vivo models of EOC. Platinum-based chemotherapy synergizes with ErbB-targeted CAR T cells (named T4), significantly reducing tumor burden in mice. Here, we show that paclitaxel synergizes with T4 as well, and look into the mechanisms behind the effectiveness of chemo-immunotherapy in our system. Impairment of caspase activity using pan-caspase inhibitor Z-VAD reveals this chemotherapy-induced apoptotic pathway as an essential factor in driving synergy. Mannose-6-phosphate receptor-mediated autophagy and the arrest of cell cycle in G2/M are also shown to be induced by chemotherapy and significantly contributing to the synergy. Increased expression of PD-1 on T4 CAR T cells occurred when these were in culture with ovarian tumor cells; on the other hand, EOC cell lines showed increased PD-L1 expression following chemotherapy treatment. These findings provided a rationale to look into testing PD-1 blockade in combination with paclitaxel and T4 immunotherapy. Combination of these three agents in mice resulted in significant reduction of tumor burden, compared to each treatment alone. In conclusion, the mechanism driving synergy in chemo-immunotherapy of EOC is multifactorial. A deeper understanding of such process is needed to better design combination therapies and carefully stratify patients.

Combination therapy: A feasibility strategy for CAR-T cell therapy in the treatment of solid tumors

Chimeric antigen receptor (CAR) T-cell therapies have been demonstrated to have durable and potentially curative therapeutic efficacies in patients with hematological malignancies. Currently, multiple clinical trials in CAR-T cell therapy have been evaluated for the treatment of patients with solid malignancies, but have had less marked therapeutic effects when the agents are used as monotherapies. When summarizing relevant studies, the present study found that combination therapy strategies for solid tumors based on CAR-T cell therapies might be more effective. This review will focus on various aspects of treating solid tumors with CAR-T cell therapy: i) The therapeutic efficacy of CAR-T cell monotherapy, ii) the feasibility of the CAR-T cell therapy in conjunction with chemotherapy, iii) the feasibility of CAR-T cell therapy with radiotherapy, iv) the feasibility of CAR-T cell therapy with chemoradiotherapy, and v) the feasibility of the combination of CAR-T cell therapy with other strategies.

Perspectives on Chimeric Antigen Receptor T-Cell Immunotherapy for Solid Tumors

Chimeric antigen receptor (CAR) T-cell therapy entails the genetic engineering of a patient's T-cells to express membrane spanning fusion receptors with defined specificities for tumor-associated antigens. These CARs are capable of eliciting robust T-cell activation to initiate killing of the target tumor cells. This therapeutic approach has produced unprecedented clinical outcomes in the treatment of "liquid" hematologic cancers, but to date has not produced comparable responses in targeting solid malignancies. Advances in our understanding of the immunobiology of solid tumors have highlighted several hurdles which currently hinder the efficacy of this therapy. These barriers include the insufficient accumulation of CAR T-cells in the tumor due to poor trafficking or physical exclusion and the exposure of infiltrating CAR T-cells to a panoply of immune suppressive checkpoint molecules, cytokines, and metabolic stresses that are not conducive to efficient immune reactions and can thereby render these cells anergic, exhausted, or apoptotic. This mini-review summarizes these hurdles and describes some recent approaches and innovations to genetically re-engineer CAR T-cells to counter inhibitory influences found in the tumor microenvironment. Novel immunotherapy drug combinations to potentiate the activity of CAR T-cells are also discussed. As our understanding of the immune landscape of tumors improves and our repertoire of immunotherapeutic drugs expands, it is envisaged that the efficacy of CAR T-cells against solid tumors might be potentiated using combination therapies, which it is hoped may lead to meaningful improvements in clinical outcome for patients with refractory solid malignancies.

Application of chimeric antigen receptor-engineered T cells in ovarian cancer therapy

Due to the critical role of T cells in the immune surveillance of ovarian cancer, adoptive T-cell therapies are receiving increased attention as an immunotherapeutic approach for ovarian cancer. Chimeric antigen receptors (CARs), constructed by incorporating the single-chain Fv fragment to a T-cell signaling domain such as CD3 ζ or Fc receptor γ chain, endow T cell with nonmajor histocompatibility complex-restricted specificity. Dual specificity, trans-signaling CARs and affinity-tuned single-chain Fv fragment have broadened the applicability of CAR-engineered T-cell therapy and may be considered preferential to T cell receptor T-cell therapy in clinical care. As new insights into the CAR-engineered T cells have emerged over the last decade, we review the development of CAR T-cell therapy and discuss the progress and safety concerns regarding its translation from basic research into clinical care of ovarian cancer.

Advances in the use of natural receptor- or ligand-based chimeric antigen receptors (CARs) in haematologic malignancies

Chimeric antigen receptors (CAR)-T cell therapy has recently made promising advances towards treatment of B-cell malignancies. This approach makes use of an antibody-derived single chain variable fragment (scFv)-based CAR to target the CD19 antigen. Currently scFvs are the most common strategy for creation of CARs, but tumor cells can also be targeted using non-antibody based approaches with designs focused on the interaction between natural receptors and their ligands. This emerging strategy has been used in unique ways to target multiple tumor types, including solid and haematological malignancies. In this review, we will highlight the performance of receptor-ligand combinations as designs for CARs to treat cancer, with a particular focus on haematologic malignancies.

'Atypical' CAR T cells: NKG2D and Erb-B as examples of natural receptor/ligands to target recalcitrant solid tumors

Chimeric antigen receptor (CAR) T-cell therapy has recently been recommended for approval for certain B-cell malignancies bringing the approach closer to mainstream cancer treatment. This rapid rise to prominence has been driven by impressive clinical results and the means to successfully commercialize the approach now being actively pursued. The current success of CAR T cells in B-cell malignancies relies upon the absolute lineage specificity of the CD19 antigen. CARs can also be targeted using non-antibody approaches, including the use of receptors and ligands to provide target specificity that have different specificities and binding kinetics. The specific examples of NKG2D and Erb-B are used that provide different characteristics and target profiles for CAR T-cell therapy of cancer.

Intracavitary 'T4 immunotherapy' of malignant mesothelioma using pan-ErbB re-targeted CAR T-cells

Malignant mesothelioma remains an incurable cancer. We demonstrated that mesotheliomas expressed EGFR (79.2%), ErbB4 (49.0%) and HER2 (6.3%), but lacked ErbB3. At least one ErbB family member was expressed in 88% of tumors. To exploit ErbB dysregulation in this disease, patient T-cells were engineered by retroviral transduction to express a panErbB-targeted chimeric antigen receptor (CAR), co-expressed with a chimeric cytokine receptor that allows interleukin (IL)-4 mediated CAR T-cell proliferation. This combination is referred to as T4 immunotherapy. T-cells from mesothelioma patients were uniformly amenable to T4 genetic modification and expansion/enrichment thereafter using IL-4. Patient-derived T4⁺ T-cells were activated upon contact with a panel of four mesothelioma cell lines, leading to cytotoxicity and cytokine release in all cases. Adoptive transfer of T4 immunotherapy to SCID Beige mice with an established bioluminescent LO68 mesothelioma xenograft was followed by regression or eradication of disease in all animals. Despite the established ability of T4 immunotherapy to elicit cytokine release syndrome in SCID Beige mice, therapy was very well tolerated. These findings provide a strong rationale for the clinical evaluation of intracavitary T4 immunotherapy to treat mesothelioma.

Targeting of Aberrant αvβ6 Integrin Expression in Solid Tumors Using Chimeric Antigen Receptor-Engineered T Cells

Expression of the αvβ6 integrin is upregulated in several solid tumors. In contrast, physiologic expression of this epithelial-specific integrin is restricted to development and epithelial re-modeling. Here, we describe, for the first time, the development of a chimeric antigen receptor (CAR) that couples the recognition of this integrin to the delivery of potent therapeutic activity in a diverse repertoire of solid tumor models. Highly selective targeting αvβ6 was achieved using a foot and mouth disease virus-derived A20 peptide, coupled to a fused CD28⁺CD3 endodomain. To achieve selective expansion of CAR T cells ex vivo, an IL-4-responsive fusion gene (4αβ) was co-expressed, which delivers a selective mitogenic signal to engineered T cells only. In vivo efficacy was demonstrated in mice with established ovarian, breast, and pancreatic tumor xenografts, all of which express αvβ6 at intermediate to high levels. SCID beige mice were used for these studies because they are susceptible to cytokine release syndrome, unlike more immune-compromised strains. Nonetheless, although the CAR also engages mouse αvβ6, mild and reversible toxicity was only observed when supra-therapeutic doses of CAR T cells were administered parenterally. These data support the clinical evaluation of αvβ6 re-targeted CAR T cell immunotherapy in solid tumors that express this integrin.

CAR T-cell immunotherapy: The path from the by-road to the freeway?

Chimeric antigen receptors are genetically encoded artificial fusion molecules that can re-program the specificity of peripheral blood polyclonal T-cells against a selected cell surface target. Unparallelled clinical efficacy has recently been demonstrated using this approach to treat patients with refractory B-cell malignancy. However, the approach is technically challenging and can elicit severe toxicity in patients. Moreover, solid tumours have largely proven refractory to this approach. In this review, we describe the important structural features of CARs and how this may influence function. Emerging clinical experience is summarized in both solid tumours and haematological malignancies. Finally, we consider the particular challenges imposed by solid tumours to the successful development of CAR T-cell immunotherapy, together with a number of innovative strategies that have been developed in an effort to reverse the balance in favour of therapeutic benefit.

Chimeric antigen receptors: On the road to realising their full potential

Chimeric antigen receptors (CARs) are fusion molecules that may be genetically delivered ex-vivo to T-cells and other immune cell populations, thereby conferring specificity for native target antigens found on the surface of tumour and other target cell types. Antigen recognition by CARs is neither restricted by nor dependent upon human leukocyte antigen antigen expression, favouring widespread use of this technology across transplantation barriers. Signalling is delivered by a designer endodomain that provides a tailored and target-dependent activation signal to polyclonal circulating T-cells. Recent clinical data emphasise the enormous promise of this emerging immunotherapeutic strategy for B-cell malignancy, notably acute lymphoblastic leukaemia. In that context, CARs are generally targeted against the ubiquitous B-cell antigen, CD19. However, CAR T-cell immunotherapy is limited by potential for severe on-target toxicity, notably due to cytokine release syndrome. Furthermore, efficacy in the context of solid tumours remains unproven, owing in part to lack of availability of safe tumour-specific targets, inadequate CAR T-cell homing and hostility of the tumour microenvironment to immune effector deployment. Manufacture and commercial development of this strategy also impose new challenges not encountered with more traditional drug products. Finally, there is increasing interest in the application of this technology to the treatment of non-malignant disease states, such as autoimmunity, chronic infection and in the suppression of allograft rejection. Here, we consider the background and direction of travel of this emerging and highly promising treatment for malignant and other disease types.

Past, present and future targets for immunotherapy in ovarian cancer

Ovarian cancer is the leading cause of death from gynecologic malignancy in the US. Treatments have improved with conventional cytotoxic chemotherapy and advanced surgical techniques but disease recurrence is common and fatal in nearly all cases. Current evidence suggests that the immune system and its ability to recognize and eliminate microscopic disease is paramount in preventing recurrence. Ovarian cancer immunotherapy is targeting tumors through active, passive and adoptive approaches. The goal of immunotherapy is to balance the activation of the immune system against cancer while preventing the potential for tremendous toxicity elicited by immune modulation. In this paper we will review the different immunotherapies available for ovarian cancer as well as current ongoing studies and potential future directions.

Ovarian cancer immunotherapy using PD-L1 siRNA targeted delivery from folic acid-functionalized polyethylenimine: strategies to enhance T cell killing

Adoptive T cell immunotherapy is a promising treatment strategy for epithelial ovarian cancer (EOC). However, programmed death ligand-1 (PD-L1), highly expressed on EOC cells, interacts with programmed death-1 (PD-1), expressed on T cells, causing immunosuppression. This study aims to block PD-1/PD-L1 interactions by delivering PD-L1 siRNA, using various folic acid (FA)-functionalized polyethylenimine (PEI) polymers, to SKOV-3-Luc EOC cells, and investigate the sensitization of the EOC cells to T cell killing. To enhance siRNA uptake into EOC cells, which over express folate receptors, PEI is modified with FA or PEG-FA so that siRNA is complexed into nanoparticles with folate molecules on the surface. PEI modification with a single functional group lowers the polymer cytotoxicity compared to unmodified PEI. FA-conjugated polymers increase siRNA uptake into SKOV-3-luc cells and decrease unspecific uptake into monocytes. All polymers result in 40% to 50% PD-L1 protein knockdown. Importantly, SKOV-3-Luc cells treated with either PEI-FA or PEI- polyethylene glycol (PEG)-FA/PD-L1 siRNA complexes are up to twofold more sensitive to T cell killing compared to scrambled siRNA treated controls. These findings are the first to demonstrate that PD-L1 knockdown in EOC cells, via siRNA/FA-targeted delivery, are able to sensitize cancer cells to T cell killing.

ErbB-targeted CAR T-cell immunotherapy of cancer

Chimeric antigen receptor (CAR) based immunotherapy has been under development for the last 25 years and is now a promising new treatment modality in the field of cancer immunotherapy. The approach involves genetically engineering T cells to target malignant cells through expression of a bespoke fusion receptor that couples an HLA-independent antigen recognition domain to one or more intracellular T-cell activating modules. Multiple clinical trials are now underway in several centers to investigate CAR T-cell immunotherapy of diverse hematologic and solid tumor types. The most successful results have been achieved in the treatment of patients with B-cell malignancies, in whom several complete and durable responses have been achieved. This review focuses on the preclinical and clinical development of CAR T-cell immunotherapy of solid cancers, targeted against members of the ErbB family.

Clinical Evaluation of ErbB-Targeted CAR T-Cells, Following Intracavity Delivery in Patients with ErbB-Expressing Solid Tumors

Adoptive cell therapy using gene-modified T-cells has achieved impressive results in the treatment of B-cell malignancies. However, the development of similar strategies to treat solid tumors raises challenges with respect to tumor antigen selection and the achievement of efficient T-cell homing, survival and sustained effector function within the tumor microenvironment. To address these challenges, we have developed a gene-modified cellular therapy called T4 immunotherapy. To generate T4 immunotherapy, autologous T-cells are engineered by retroviral transduction to co-express two transgenes: (1) a chimeric antigen receptor (CAR), T1E28z, targeted against a range of ErbB homodimers and heterodimers and (2) a chimeric cytokine receptor, 4αβ, that allows the selective ex vivo expansion of engineered cells using interleukin-4. Targeting of the extended ErbB network using CAR T-cells is supported by prevalence of ErbB dysregulation in diverse solid tumors and the clinical impact of monoclonal antibody therapy directed against members of this family. However, the key obstacle to effective clinical translation is risk of on-target toxicity owing to the lower level expression of ErbB family members in many healthy tissues. To de-risk T4 immunotherapy in man, we are undertaking a trial in patients with locally advanced or recurrent head and neck squamous cell carcinoma. In that setting, engineered T-cells are injected directly into the tumor without prior lymphodepletion, an approach that we believe will minimize risk of toxicity. This chapter outlines how we plan to advance the development of T4 immunotherapy thereafter in Phase II clinical testing. In that setting, regional (intracavitary) approaches will be used to administer this therapy to patients with epithelial ovarian cancer and malignant pleural mesothelioma.

Adoptive Immunotherapy of Epithelial Ovarian Cancer with Vγ9Vδ2 T Cells, Potentiated by Liposomal Alendronic Acid

Adoptive immunotherapy using γδ T cells harnesses their natural role in tumor immunosurveillance. The efficacy of this approach is enhanced by aminobisphosphonates such as zoledronic acid and alendronic acid, both of which promote the accumulation of stimulatory phosphoantigens in target cells. However, the inefficient and nonselective uptake of these agents by tumor cells compromises the effective clinical exploitation of this principle. To overcome this, we have encapsulated aminobisphosphonates within liposomes. Expanded Vγ9Vδ2 T cells from patients and healthy donors displayed similar phenotype and destroyed autologous and immortalized ovarian tumor cells, following earlier pulsing with either free or liposome-encapsulated aminobisphosphonates. However, liposomal zoledronic acid proved highly toxic to SCID Beige mice. By contrast, the maximum tolerated dose of liposomal alendronic acid was 150-fold higher, rendering it much more suited to in vivo use. When injected into the peritoneal cavity, free and liposomal alendronic acid were both highly effective as sensitizing agents, enabling infused γδ T cells to promote the regression of established ovarian tumors by over one order of magnitude. Importantly however, liposomal alendronic acid proved markedly superior compared with free drug following i.v. delivery, exploiting the “enhanced permeability and retention effect” to render advanced tumors susceptible to γδ T cell–mediated shrinkage. Although folate targeting of liposomes enhanced the sensitization of folate receptor–α+ ovarian tumor cells in vitro, this did not confer further therapeutic advantage in vivo. These findings support the development of an immunotherapeutic approach for ovarian and other tumors in which adoptively infused γδ T cells are targeted using liposomal alendronic acid.

Design of a phase I clinical trial to evaluate intratumoral delivery of ErbB-targeted chimeric antigen receptor T-cells in locally advanced or recurrent head and neck cancer

Despite several advances, 5-year survival in patients with head and neck squamous cell carcinoma (HNSCC) remains unchanged at only 50%. The commonest cause of death is locally advanced/recurrent disease. Consequently, there is an unmet need for new approaches to improve local control in HNSCC. T4 immunotherapy is an autologous cell therapy in which peripheral blood T-cells are genetically engineered using a retroviral vector to coexpress two chimeric receptors: (i) T1E28z is a chimeric antigen receptor that engages multiple ErbB dimers that are commonly upregulated in HNSCC; (ii) 4αβ is a chimeric cytokine receptor that converts the weak mitogenic stimulus provided by interleukin (IL)-4 into a strong and selective growth signal, allowing preferential expansion and enrichment of T4(+) T-cells ex vivo. T4 immunotherapy exerts antitumor activity against HNSCC cell lines and tumors in vivo, without significant toxicity. Human T4(+) T-cells also engage mouse ErbB receptors, permitting safety testing in SCID Beige mice. Severe toxicity caused by cytokine release syndrome ensues when human T4(+) T-cells are administered at high doses to mice, particularly with advanced tumor burdens. However, such toxicity is not required for efficacy and is never seen if T-cells are administered by the intratumoral route. To exploit this, we have designed a first-in-man clinical trial in which T4(+) T-cells are administered to patients with locally advanced/recurrent HNSCC. Cells will be administered at a single sitting to multiple sites around the viable tumor circumference. A 3+3 dose escalation design will be used, starting at 10(7) cells (cohort 1), escalating to 10(9) cells (cohort 5). If maximum tolerated dose remains undefined, cohorts 6/7 will receive either low- or high-dose cyclophosphamide before 10(9) T4(+) T-cells. A panel of routine/in-house assays and imaging techniques will be used to monitor safety, efficacy, perturbation of endogenous antitumor immunity, immunogenicity, and T-cell trafficking.

Preclinical in vivo modeling of cytokine release syndrome induced by ErbB-retargeted human T cells: identifying a window of therapeutic opportunity?

The ErbB network is dysregulated in many solid tumors. To exploit this, we have developed a chimeric Ag receptor (CAR) named T1E28z that targets several pathogenetically relevant ErbB dimers. T1E28z is coexpressed with a chimeric cytokine receptor named 4αβ (combination termed T4), enabling the selective expansion of engineered T cells using IL-4. Human T4(+) T cells exhibit antitumor activity against several ErbB(+) cancer types. However, ErbB receptors are also expressed in several healthy tissues, raising concerns about toxic potential. In this study, we have evaluated safety of T4 immunotherapy in vivo using a SCID beige mouse model. We show that the human T1E28z CAR efficiently recognizes mouse ErbB(+) cells, rendering this species suitable to evaluate preclinical toxicity. Administration of T4(+) T cells using the i.v. or intratumoral routes achieves partial tumor regression without clinical or histopathologic toxicity. In contrast, when delivered i.p., tumor reduction is accompanied by dose-dependent side effects. Toxicity mediated by T4(+) T cells results from target recognition in both tumor and healthy tissues, leading to release of both human (IL-2/IFN-γ) and murine (IL-6) cytokines. In extreme cases, outcome is lethal. Both toxicity and IL-6 release can be ameliorated by prior macrophage depletion, consistent with clinical data that implicate IL-6 in this pathogenic event. These data demonstrate that CAR-induced cytokine release syndrome can be modeled in mice that express target Ag in an appropriate distribution. Furthermore, our findings argue that ErbB-retargeted T cells can achieve therapeutic benefit in the absence of unacceptable toxicity, providing that route of administration and dose are carefully optimized.